The present invention relates generally to constant fuel-air ratio, rotor-type carburetors utilized in internal combustion engines, and more particularly provides an improved rotor-type carburetor having an adjustable fuel-air ratio, a mechanism for diminishing unwanted fuel discharge therefrom during periods of rotor spin-down, and for enhancing fuel delivery during initial rotor spin-up periods, as well as various other structural improvements.
The rotor-type carburetor, also referred to as a "central injection device", has been proposed, in various versions thereof, as a as a replacement for the conventional carburetor in a variety of internal combustion spark ignition engines because of its very advantageous provision of an essentially constant fuel-air ratio (.lambda.) at all operating speeds of the engine. In its basic operating format, the rotor-type carburetor is provided with a bladed turbine rotor section which is coaxially and rotationally disposed in the air intake passage of the engine upstream of the butterfly damper therein. During operation of the engine, ambient air drawn inwardly through the engine's air intake passage causes rapid rotation of the bladed rotor section. A centrifugal pumping mechanism formed within the rotor draws fuel from a source thereof into the rotor and forces the received fuel outwardly there through, via at least one lateral fuel discharge bore, onto and across a coaxial atomization or spray into the ingested air stream. Importantly, the quantity of finely atomized fuel entering the air stream is in an essentially constant ratio to the ingested quantity of air, thereby essentially eliminating the fuel-air ratio variation problems commonly encountered in conventional carburetors.
While previously proposed rotor-type carburetors have proven to be quite effective in providing this very desirable constant fuel-air ratio benefit, it is now seen as desirable to improve various structural and operational aspects of this type of carburetor. For example, in previously proposed versions of rotor-type carburetors, a given carburetor can produce only one constant fuel-air ratio when installed in an engine. Stated otherwise, such carburetor's constant fuel air ratio is fixed.
Thus, installation of the carburetor in another engine requiring a different fuel-air ratio is precluded-a different rotor-type carburetor having a different fuel-air ratio must be fabricated and installed in the different engine. This additionally means, of course, that the constant fuel-air ratio of a given rotor-type carburetor cannot be "fine tuned" to precisely meet the exact fuel-air ratio optimally required by the engine in which it is installed.
From the foregoing, it can readily be seen that it would be quite desirable to provide a rotor-type carburetor whose constant fuel-air ratio may be selectively altered. This would afford such carburetor with the ability to be fine-tune to a particular engine in which is installed, and additionally enable the use of a particular carburetor in a variety of engines having different fuel-air ratio requirements.
Another limitation or disadvantage commonly associated with previous rotor-type carburetors is that during certain spin-down periods of their rotor, they unavoidably continue to deliver at least a very small quantity of fuel to the engine. This spin-down period may occur either when the engine is being slowed during normal operation thereof, or immediately after the engine has been shut off. This excess fuel delivery is, of course, neither necessary nor particularly desirable.
As previously mentioned, the ingested air-driven rotor section of this type of carburetor has formed therein a passageway system which defines a centrifugal pump mechanism that causes fuel to be drawn into the rotor section and discharged therefrom, via a discharge opening in the rotor section, for mixture with the engine's ingested airstream. It is important for fuel efficient operation of the carburetor that fuel outflow through the rotor section be limited to that flowing outwardly through such discharge opening. However, the typical rotor section is formed from a variety of pieces which collectively define the pump-forming internal passageway system. The junctures of these various pieces within the rotor body, of course, define a variety of potential fuel leakage paths leading from the interior of the rotor to its exterior. Accordingly, effective sealing means must be provided to block the leakage path defined by these various junctures.
While the fuel leakage sealing means utilized in previously proposed rotor structures have typically maintained the outward fuel leakage below acceptable limits, it is seen as desirable to afford the rotor assembly with even more effective sealing means.
Accordingly, it is an object of the present invention to provide an improved rotor-type carburetor, and associated methods, which provides the above-mentioned benefits and advantages, and eliminates or minimizes above-mentioned and other limitations commonly associated with previously proposed carburetors of this type.